#define _CRT_SECURE_NO_WARNINGS 1
#include<cstdio>
#include<iostream>
#include<algorithm>

using namespace std;

int main()
{
	double n = 0;
	scanf("%lf", &n);
	double l = -10000;
	double r = 10000;
	while (r - l > 1e-8)
	{
		double mid = (l + r) / 2;
		if (mid * mid * mid >= n)//pow(mid, 3)
		{
			r = mid;
		}
		else
		{
			l = mid;
		}
	}
	printf("%lf", l);
	return 0;
}